I am a Christian. I was an 8th-grade American History teacher. I am currently a freelance writer, public speaker, & homeschooling mom of 9.
This is part 2 of a 5 part hands-on unit on Inventions and Simple Machines. Build and test catapults, lift an adult using a lever, test out screws of various threads, and more! My lessons are geared toward 3rd-4th grade level children and their siblings. These are lessons I created to do with a weekly homeschool co-op. We meet each week for 2 1/2 hours and have 13 children between the ages of 1-13. Use these fun lessons with your classroom, family, after school program, camp, or co-op!
Review and Introduction
1. Stretch. Pray. Review work, inclined planes, and wedges by going through the pages of The New Way Things Work by David Macaulay.
2. Ask each child to mention something they are good at. Read & discuss James 4:10. Compare our humility for God's glory to one side of a lever. The more humble and servant-hearted we are, the more God raises us up. Mention about how God gave each of them those gifts that they said they were good at. What would be a way to use that gift to promote yourself? What would be a way to use that gift to glorify God so that He can be the one to lift you up? If desired, use a ruler placed on a triangle block (to be a lever) and use a toy person on the ruler to show this. (If you are not limited by time, talking about the Olympic sprinter and missionary Eric Liddell would way to demonstrate this.)
YOU WILL NEED: Optional visuals: a ruler, triangle block, and a toy person
3. Read "Twist, Dig, and Drill: A Book About Screws" by Michael Dahl. Ask how screws help us. What are some examples?
YOU WILL NEED: a book on screws
The book to read for activity 3
Screws Are Inclined Planes Wrapped Around a Rod
4. Make screw models using pencils and a paper triangle.
-Have each child get their sharpened pencil and crayon. Pass out a right triangle to each child.
-What simple machine does the right triangle look like? (inclined plane).
-Have them draw a line along the slanted edge of each triangle with their crayon. Have the children tape a plain edge of the triangle (3” side) to the pencil and then wrap it tightly around the pencil making sure they can see the colored line.
-Ask: What does the colored edge represent? Which distance is greater, the height of the circular inclined plane or the spiraled distance around the rolled paper?
-Explain: The screw is really a twisting plane. It is an inclined plane wrapped around a cylinder or cone. It’s a lot like a trail wrapping around a mountain. As you learned last week, an inclined plane lessens the effort needed to lift or lower something by increasing the distance over which the work is done. A screw also allows work to be done with less effort.
YOU WILL NEED: 1 sheet of paper per child cut into right angles that are about 3"x6" & items brought by families: tape, pencils, & crayons
5. (Prep: Lay out a small sheet of parchment paper or aluminum foil for each child. Use a sharpie marker to write each child’s name on one. Lay a crescent roll and a cheese stick piece on each one.) Now we are going to do the same thing you did with the pencil and paper, but this time we’re going to make screws that you can eat! Give each child 1/4 of a cheese stick and an unbaked triangle of a crescent roll. Have them roll up the crescent roll dough ("inclined plane") around the cheese stick (rod) just like they did with the pencils and paper triangle. Bake according to package directions (about 375F for 13 minutes). The children can eat these while we read about levers.
YOU WILL NEED: parchment paper or aluminum foil, sharpie marker, three 8-count packages of crescent roll dough, 6 cheese sticks (each sliced or pulled into 4 long strips), 2 large baking sheets, napkins
Comparing Screw Threads and Work
6. There are many, many uses for screws – probably more than you can imagine. What is one way that you can use a screw?
-Screw can hold materials together, drill holes into objects, open and close faucets and jars, keep light bulbs in place, and lift materials – like a regular inclined plane.
-Pass around screws or bolts that have different pitches/threads. How is each screw similar? How is each screw different? How might each screw be used? Introduce the word "pitch/thread/ridge." Does it look like there are many threads/circles or one continuous one going in a spiral?
YOU WILL NEED: 5 wood screws and 5 metal screws (The wood & metal screws should have different pitch [thread width]). *We will be using these screws for activities 7-8.*
7. Point out the difference between flat head and Philip's head screwdrivers. Divide children into 5 groups of 4 children. Have them use their screw drivers to try to screw in the 2 screws. Ask:
-Which pitch/thread is easiest to screw: larger spaces or shorter spaces?
-Which takes more turns to screw it in?
-Which screw do you think will hold better? Why?
-Which screw has the most distance wrapped around it?
-Which requires more work?
Have them remove the screws for the next activity.
-Explain that the metal screw is used for building things or hanging pictures. The threads of the screw turn around and around as they cut into a surface. Less effort is needed to cut into the surface because of the increased distance the threads travel.
YOU WILL NEED: 5 pieces of scrap wood that each have 8 small holes hammered into them (so that the children have a starting place to use their screws), & items brought by families: hammers & screwdrivers, & screws used for activity 6.
Screws Hold Things Together
8. How do screws help us? They hold things together. Hand each group of children 2 quarters of a Styrofoam plate.
-Have each child shove a nail through the plates to hold them together. Have them pull the 2 pieces apart. Was it easy to pull the 2 halves apart?
-Now have them screw a screw into the paper plate and then try to pull them apart. Is it easier or more difficult to pull the 2 plates apart than when the nail was holding them together?
YOU WILL NEED: 5 Styrofoam plates cut in quarters and nails (Screws will be used from above activities.)
Screws Hold Things Closed
9. Take the children outside.
-Show them the 2 lids. Ask them to hypothesize: What will happen when I stand at the top of this ladder and drop each of these jugs?
-Climb to the top of the ladder and drop them both.
-What did we just learn is one function of a screw? Yes, it can hold things closed.
-Go back inside. Ask, “How many other examples of screws that fasten can you name?” Show a light bulb, a jar lid, a tube of toothpaste, etc.
YOU WILL NEED: 2 plastic jugs *One should have a screw lid & one should have a snap on lid.* and examples of screws that fasten such as a light bulb, jar lid, tube of toothpaste, etc.
*Note: The first time we did this, we used 2 vinegar bottles and dropped them off a two story building. The screw on lid stayed on. The second time we did this, we used gallon milk jugs and dropped them off a 6 foot ladder. The screw lid came off!*
10. Read some of the picture book on Archimedes: Archimedes by Susan Keating.
YOU WILL NEED: Archimedes by Susan Keating
11. Show how an Archimedes screw/auger works.
-Ahead of time create an auger. If you have extra time you can let each child make one, but I just made one ahead of time with my children. We let everyone turn it around a few times to draw up Rice Krispies so they could see how it works. To make an auger, follow the directions on p. 10 of "Science Book of Machines" by Ardley. Cut the top and bottom off a 2-liter bottle. Trace the open bottle circle onto a piece of cardstock and cut out 6 circles that size. On each circle, trace the bottom of the dowel rod onto the middle of the circles and cut a line into the middle of each circle and cut out a small circle in the middle that is the size of the dowel rod. Lay the circles on top of each other and tape the opposite cut sides of the circle to the circle below it. Pull the circles apart so that you have a screw/continuous spiral. Tape the top and bottom circle slit to the rod. Place it inside the cut 2 liter bottle. Place your auger in a large bowl of Rice Krispies and turn it in circles to spin the cereal to the top of the auger.
YOU WILL NEED: 1 auger (directions above) and 1 large bowl of Rice Krispies
13. (If you have extra time) Screws also push. Demonstrate how a screw pushes. (On p. 38 in Sensational Science Projects with Simple Machines by Gardner.)
Lifting with Levers
14. Hand a child a shovel and a brick and tell them to lift you off the floor without touching you. Let each child try. Try moving the brick (fulcrum) closer to the child and then have them try to lift you again. What happened? (*Have an adult stand on each side of you and hold your hands to keep you balanced.*)
-You just made a simple machine called a lever! Levers are used in many, many simple and compound machines. A lever is simply a bar that goes up and down over a point. That point is called the fulcrum [Have children repeat, “fulcrum.”] The brick was the fulcrum. The load is the thing being lifted – me! You created a first-class lever, one of the most useful levers. (Note: The two times we have done this, we have had a 3 year old lift their mothers!)
YOU WILL NEED: a shovel or a sturdy piece of plywood about that length and a brick
15. Archimedes not only invented a type of screw to raise up items, but he also discovered the value and importance of levers. He is famous for saying, “Give me a place to stand, and I will move the earth.” He used levers to create simple and compound machines. First-class levers were used as catapults to launch rocks onto Roman ships as they came into port. With practice, they could aim the rocks exactly where they wanted them to go. At the end of class we’ll be making our own versions of those catapults, but let’s first learn about levers.
-Read Scoop, Seesaw, and Raise: A Book About Levers by Michael Dahl. How do levers help us? What are some examples?
YOU WILL NEED: Scoop, Seesaw, and Raise: A Book About Levers by Michael Dahl
Book to read for activity 15
The Lever Brothers: Efl, Elf, and Fel
16. Explain that there are 3 types of levers. The difference between the 3 levers is where the fulcrum is located.
-Use 3 stuffed animals or toy people and suggested props to use as you tell this story. These are the 3 Lever brothers: Efl (“effel”) Lever, Elf Lever, and Fel Lever. Their parents named them in alphabetical order. [Have the children repeat the names Efl, Elf, and Fel two times.] Efl, Elf, and Fel found this huge fish flopping around on the shore of a lake. They need to get back into the lake! Efl suggests they put the fish on one end of a seesaw. On the count of 3 all of them jump on the other end, and the fish will fly up into the ocean. [Demonstrate this using a ruler on a block as the lever. The kids loved watching the fish fly through the air!] "No, no, no!" shouts the second brother, Elf. "Just lift the fish into my wheelbarrow, and I can easily push it over to the dock and drop it in." [Use a bowl or a picture of a wheelbarrow and show Elf pushing the fish along in it.] The third brother, Fel, gets a guilt look on his face. He quickly pulls out his fishing rod, drops a hook in the fish's mouth, and runs away to announce to all his friends about the enormous fish he just caught!
-That’s a silly story, isn’t it? Hopefully it will help you remember the 3 classes of levers. The first brother’s name, Efl, stands for the first class lever, which has the effort, fulcrum, and then load. The effort is what you’re touching to do the work, the fulcrum is the part that doesn’t move, and the load is whatever you are trying to lift or move. In our story, what was the load? Yes, it was the fish. What did Efl suggest they use to move the fish? Yes, a seesaw. A seesaw is a first class lever.
-What was the name of the second brother? Elf. A second class lever has the effort, load, and then fulcrum. What did he suggest they use to move the fish? A wheelbarrow, which is a second class lever. You touch the handles of the wheelbarrow, so that is the E for effort. The load, the fish, would be in the middle. The end that holds the wheel in the front stays in place, so it is the fulcrum.
-What was the name of the devious third brother? Fel. What did he use? A fishing pole. That’s a third class lever. The fulcrum is the handle of the fishing pole. You put your hands further up on the pole, so that is your effort. Your load, the fish, is at the end of the pole.
YOU WILL NEED: 3 stuffed animals or toy people, a toy fish or picture/drawing of a fish, a ruler and toy block (can be the ones used during activity 2), toy wheelbarrow or picture of one printed from the internet or a bowl (optional), and a toy fishing rod or straw with a string hanging from it (optional)
First Class Levers
16. Explain that in a first-class lever the fulcrum is in the middle. The effort is on one side, and the object being moved (we call it the load) is on the other. Pretend that you’re on a seesaw with an NFL linebacker. How on earth would you lift him? You could! Should you move closer to him (the load) or further away? Let’s figure it out.
-Give each child a ruler, a pencil (used in the above screw activity), and a book. Have them use the pencil as a fulcrum. Place the book on one end of the ruler. Each child should push down on the opposite end while varying the distance of the fulcrum. Does your effort increase or decrease as the fulcrum moves closer to you? (The closer the fulcrum is to the object, the easier it is to lift.) The distance between you and the fulcrum is called the load arm. The distance from the fulcrum to where you are pushing is called the force/effort arm.
-You probably noticed that when the fulcrum is farther from the effort (The effort is your arm pushing on the lever), the lever works more effectively. You’re lengthening the lever arm to make the lifting easier. This allows you to lift the load with less effort. Now, back to the big NFL football player on your seesaw. If you move father from the center but the linebacker moves closer to the center, you can lift him. That’s pretty amazing, isn’t it?
YOU WILL NEED: 1 heavy book per child and sturdy rulers or pieces of wood & pencils brought by families
Second Class Levers
17. (Prep: Ahead of time tie a piece of string to each of the 5 books.) Divide children into 5 groups. Have each child lift up the book using the string. Did that take a lot of effort? It probably wasn’t super easy. Now place the string over the middle of the stick and place one end of the stick on the floor and the other up on the table. Now lift the book with the stick, lifting the part that is against the table.
-You probably found it required less effort to lift the books with the stick lever than without the help of the lever. The lever you create is a second-class lever. These levers have the load between the fulcrum (the table) and the effort (your hand).
-You’ll notice that with a second-class lever, the direction of the effort doesn’t change. You lifted the lever in the same direction as you lifted the books. With the first-class lever, you pushed down to make the load go up. With the second-class lever, you lifted the lever up as you lifted your arm. Wheelbarrows are one of the best examples of second-class levers. A nutcracker is also a class 2 lever. The nut is the load, and is in between the effort and the fulcrum. When the effort, your hand, applies a force on the handles, the other end of the nutcracker pivots to crack the nut.
YOU WILL NEED: 5 long pieces of string, 5 long sticks (such as broom or mop handles), and 5 books
Shovel or Broom as a Third Class Lever
18. OPTION 1: If you are in a location where the children can dig, go outside and have children take turns scooping dirt out of a pile using a shovel. Have them try holding the shovel with both hands at the top of the shovel and then with one hand (your lifting force) close to the bottom of the shovel. Which requires less work? This is a 3rd class lever. Your hand that is furthest out is the fulcrum. Your hand that moves is the lifting force. What is the load you're trying to lift? (dirt) Notice that with the first class lever, when you lifted me off the ground, the fulcrum was between the lifting force (you) and the load (me). Now with this 3rd class lever the lifting force (the hand you moved) is between the load (dirt) and the fulcrum (your hand that stayed still).
YOU WILL NEED: shovels or trowels
18. OPTION 2: If you are not in a location where the children can dig, have them sweep instead. Pass out the brooms that are at the church and have the children take brief turns sweeping. In class-three levers, the effort is between the load and the fulcrum. Effort is applied in between the two to move a load on the end. The fulcrum is on the left, the effort is in the middle, and the resistance force is on the end. Effort is applied by your hands when you hold the handle. As effort is applied, the top of the broom handle pivots to move the load at the bottom of the broom. Another great example is your uniquely designed arm. God created a third-class lever when He made your arm. When you lift a glass of water to your mouth, the fulcrum is your elbow. Remember, the fulcrum is the place where the bar pivots or turns. The effort is where the muscles of your forearm attach to your bones. The load is the glass of water in your hand.
YOU WILL NEED: brooms
Catapults as Levers
19. Show various types of catapults. (We made examples of some of the below catapults.) Lay out the items and let children have 10-15 minutes to create a catapult, which is a type of lever. Afterward, give everyone 2 large marshmallows. Write their initials using a sharpie marker on one marshmallow. Let them eat the other one. Line them up and have them test out their catapults using large marshmallows as the "rocks." See who can propel the marshmallow the furthest. Then place a shoe-box size container where most of the marshmallows landed. Tell them this bucket is a Roman ship that has come to invade their land. Who can hit it? Let them propel their marshmallow again and try to aim for the bucket. See whose catapult is the most accurate.
YOU WILL NEED: sharpie marker, 1 bag of large marshmallows, bag of rubber bands of various sizes, 24 large binder clips, pieces of 12-inch string/yarn, 150+ craft/popsicle sticks, 20 plastic spoons, 3 rolls of masking tape, 6 screw-on lids (like ones from a 2 liter soda bottle), 20 disposable cups, wooden shish-kabob sticks or dowel rods, & examples of some of the below catapults:
Clothes Pin Catapult - A few children tried this model. It works best if you tilt it upward rather than lay it flat.
A few simple options for catapults - We made a version of the spoon catapult.
Homeschool Lesson on Catapults with Many Examples
Rubber Band Catapult
Triangle Catapult - This one is a bit more complex but could be done by one of the older children.
20. If you are not limited by time, read through parts of the book Castle Under Siege!: Simple Machines by Andrew Solway.
Simple Machines Song & Review
21. Sing Simple Machines Song & Review.
Simple Machines Song Tune: Yankee Doodle
When it's moved by force we call it work,
but here's what I've been told:
Use any simple machine to help and ease that heavy load.
Wheel and axle, pulley, wedge
Screw, inclined plane, lever
When you learn to use simple machines
You'll show you are so clever.
The inclined plane is like a ramp,
a ladder, stairs, or hill.
Increase the distance = reduce the work.
Mechanical Advantage thrill.
The wedge is used to separate,
lift, or hold in place.
You use a wedge to cut your cakes,
Long and narrow = less force it takes.
Our levers come three different ways,
depending on the fulcrum.
Lift, squeeze, cut, pull, haul, or toss
to get all of that work done.
The screw just turns to do its job
- like opening your juice.
Or use the screw to hold things tight,
so that they won't get loose.
(The song is a variation from this lesson : http://www.uen.org/Lessonplan/preview.cgi?LPid=9700.)
22. Review: What simple machine is used to make a screw? What are some examples of screws? How can screws help us? Who invented a type of screw that can be used to lift things? What other simple machine did we learn about today? How many types of levers are there? What were the names of the 3 Lever brothers? What did the E stand for? The F? The L? Name an example of a first class lever? A second class lever? A third class lever? What was your favorite activity we did today?
Homework: Simple Machines Lapbook
If you'd like to create a Simple Machines lapbook this week, here are some options:
Material List for the Lesson
Everyone please bring per child:
-a sharpened pencil (preferably a newly sharpened one – NOT a mechanical pencil)
-scotch tape (1 roll per family)
-screwdriver(s) – cross blade/Philips head (1 per family or more if you have them)
-a sturdy ruler
-Optional: If you have hex-head screws or screwdrivers, vises or c-clamps, or an auto jack, please bring them to show to the children.
Items to bring to share with the class:
-Book: The New Way Things Work by David Macaulay.
-wooden block triangle and toy person (optional)
-Book: Twist, Dig, and Drill: A Book About Screws by Michael Dahl
-per child: sheet of paper cut into right angle that is about 3"x6"
-parchment paper or aluminum foil, sharpie marker, three 8-count packages of crescent roll dough, 6 cheese sticks (each sliced or pulled into 4 long strips), 2 large baking sheets, napkins
-5 wood screws and 5 metal screws (The wood & metal screws should have different pitch [thread width])
-5 pieces of scrap wood that each have 8 small holes hammered into them (so that the children have a starting place to use their screws)
-5 Styrofoam plates cut in quarters and nails
-2 plastic jugs *One should have a screw lid & one should have a snap on lid.* and examples of screws that fasten such as a light bulb, jar lid, tube of toothpaste, etc.
-Book: Archimedes by Susan Keating.
-1 auger (directions in lesson) and 1 large bowl of Rice Krispies
-a shovel or a sturdy piece of plywood about that length and a brick
-Book: Scoop, Seesaw, and Raise: A Book About Levers by Michael Dahl
-3 stuffed animals or toy people, a toy fish or picture/drawing of a fish, and a ruler and toy block
-1 heavy book per child
-5 long pieces of string, 5 long sticks (such as broom or mop handles), and 5 books
-shovels or trowels OR brooms
-sharpie marker, 1 bag of large marshmallows, bag of rubber bands of various sizes, 24 large binder clips, pieces of 12-inch string/yarn, 150+ craft/popsicle sticks, 20 plastic spoons, 3 rolls of masking tape, 6 screw-on lids (like ones from a 2 liter soda bottle), 20 disposable cups, wooden shish-kabob sticks or dowel rods, & examples of catapults
Book to Use for This Entire Unit Study on Simple Machines
Homework: Great Sets for Educational Play Afterward
If you'd like to get something your children will play with over and over again after this lesson, get one of these. The K'NEX Education - Intro To Simple Machines: Levers and Pulleys (pictured on the right) is wonderful! My kids love these and build with them over and over again! The set lets them experiment with 8 functioning lever and pulley models and includes a lesson plan booklet to help.
Engino Mechanical Science: Screws is a really fun set that my boys love! It has 5 working models that you can build. It also includes a screw press, 2 cranes, a vice, and a folding lifting platform. *Also look for Engino Mechanical Science: Levers, which teaches how levers are used to increase force and lift heavy objects and how the use of levers can change the direction of motion. Build 6 working models including a parking gate, a see-saw, 2 types of scales and a wheelbarrow. A 40 page activity book is included with experiments and detailed explanations.
More Good Children's Books on Screws
Simple Machines (Let's-Read-and-Find-Out Science 2) by D. J. Ward is a great picture book that covers all of the simple machines. Fred Flintstone's Adventures with Screws (Flintstones Explain Simple Machines) by Mark Weakland is a cute cartoon version describing screws and their uses. Screws to the Rescue by Sharon Thales has photographs rather than illustrations and does a good job covering both the past and the present. It's simple and educational. Screws (Early Bird Physics) by Sally M. Walker has good activity/project ideas. Sensational Science Projects With Simple Machines (Fantastic Physical Science Experiments) by Robert Gardner shows how you can use a screw to move a brick, which makes for an impressive demonstration!